Apparatus for drawing glass sheets



H. K. HITCHCOCK. APPARATUS FOR DRAWING GLASS SHEETS.

APPLICATION FILED AUG- 5, I918.

Patented Aug. 10., 1920.

FIBJ

FIEIZ.

INVENTOR UNITED STATES PATENT OFFICE.

HALBERT K. HITCHCOGK, OF PITTSBURGH, PENNSYLVANIA,

ASSIG-NOR OF ONE-HALF TO HITCHCOOK EXPERIMENT COMPANY, A CORPORATION OF NEW JERSEY.

APPARATUS FOR DRAWING GLASS SHEETS.

Application filed August 5, 1918.

To all whom it may concern.

Be it known that I, HALBERT K. HITCH- cocn, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have made a new and useful Invention in Apparatus for Drawing Glass Sheets, of which the following is a specification.

The invention relates to apparatus for drawing of glass sheets and particularly to that part of the apparatus from which the sheet is generated. The invention has for its principal objects, the provision of a drawing receptacle, (1) adapted to secure a greater degree of cooling at the edges, which cooling permits the formation of thicker edges, assists in holding the glass flat, and

counteracts the normal tendency of the sheet to draw in and narrow in width as the drawing of the sheet progresses, and (2) adapted to secure a better adhesion between the sheet at its edges, also tending to prevent a narrowing of the sheet at the line of generation of the sheet. One embodiment of the invention is illustrated in the accompanying drawings wherein:

Figure 1 is a plan view of the drawing receptacle, Fig. 2 is a side view of onehalf of the drawing receptacle with the supply chamber therebeneath in section, and Fig. 3 is a transverse section through the drawing receptacle and passage or supply chamber.

For convenience in construction the drawing receptacle is made in two sections, 11 joined together along the line 2 (Fig. 1). This receptacle .comprises two side walls 33, preferably made double or hollow to provide the heating chambers 4-4. These chambers may be heated by means of the gas pipes 5, the openings 6 at the tops of the chambers permitting of the escape of the products of combustion.

The end walls 1 of the receptacle are preferably made of single thickness, and as indicated in Fig. 2 are cut away at 7 to a level below that of the side walls 3. This is to facilitate the more rapid cooling of the edges of the sheet of glass, the low walls at the ends permitting a more rapid radiation of heat. In order to still further facilitate the cooling of the edges the slots 8 are provided extending down preferably to a level below the glass level in the receptacle as indicated by the dotted line 10 in Fig. 2. Before the Specification of Letters Patent.

Patented Aug. 10, 1920. Serial No. 248,444.

8 resting against the outer surface of thecontainer at these points or by means of plugs or gates fitting down into the slots. After the drawrng is started, the plates or plugs may be wlthdrawn, and the chilled glass in the slots serves as closure means therefor. The depth to which these slots are out below the surface of the glass in the receptacle will depend upon the conditions of each particular case, including the temperature of the glass, the speed of drawing, and the width of the slots.

The dotted lines 11 indicate the glass sheet being generated, but it will be understood that this is merely diagrammatic and that the curves described at the edges of the sheet w1ll vary depending upon the conditions. The drawing of the sheet may be started by means of any of the types of baits known in the art and the drawing continued by any means suitable for the continuous application of drawing force to the sheet. The receptacle is supplied with glass through the slot 12 leading into the chamber or passage 13 beneath, such chamber or passage leading to a melting tank.

he side walls of the receptacle may be regulated in temperature to suit requirements, while the construction of the end walls facilitates the cooling of the edges of the glass as compared with the central portion of the sheet and serves to improve the connection between the edges of the sheet and the ends of the receptacle. Even when the walls 4 are not heated, as may some times be the case, such walls, because of the chambers formed therein, serve to retain the heat better than is the case with walls of single thickness, so that this construction in connection with the height of the side walls as compared with that of the end walls, serves to maintain the temperature of the main body of glass in the pot and to keep the central portion of the sheet at a somewhat higher temperature than the edges. The cooled and thickened edges, which are necessarily formed by reason of the foregoing construction, tend to maintain the width of the sheet and to provide a stretching action upon the portion of the sheet lying between the edges, thus removing the lines which are commonly formed when the sheet of glass is drawn from a molten bath in proximity to a body of clay. The relatively cool envelop of glass, which is formed 1n drawlng from a receptacle of this type, and whose mter or is fed from the hotter glass beneath the line of generation of the sheet, adheres to the clay receptacle both at the sides and the end, so that when tension 1s applied to stretch the glass of the envelop, the tendency of the edges is to draw in unless such edges are substantially thicker and more resistant than the sides of the envelop, so that the more rapid cooling of the edges and the thickening thereof is necessary if they are to maintain their position without mechanical assistance. The slots 8 are filled with chilled glass which permits a better transmission of heat and a more rapid cooling of the adjacent glass than is the case with an opposing body of clay, and this body of chilled glass also forms an anchorage for the edge of a glass sheet which is more secure than afforded by a body of clay.

Since the edges of a sheet being drawn radiate the heat more rapidly than the central portion thereof, the sheet normally tends to buckle due to the unequal cooling and correspondingly unequal contraction. With the thickened edges as produced by the present apparatus this difficulty is overcome in that the thickened edges, produced by the rapid cooling at the initiation of the draw, contain a greater amount of heat in proportion to their radiating surfaces than the body-of the sheet. As a result the temperature is more uniform from edge to edge than is the case with a sheet of uniform thickness from edge to edge.

What I claim is:

1. A container for glass approximating in length the width of the glass sheet to be produced and comprising side walls and end walls of refractory material with the end walls slotted to a level below that of the body of glass in the container and in alinement with the line of generation of the glass sheet to be drawn, the said slots being of such restricted width that the glass filling them solidifies.

2. A container for glass approximating in length the width of the glass sheet to be produced and comprising side walls and end walls of refractory material with the end walls and the end portions of the side walls cut to a level below that of the main portions of the side walls to facilitate the radiation of heat from the edges of the glass sheet drawn from the receptacle.

3. A container for glass approximating in length the width of the glass sheet to be produced and comprising side and end walls downwardly and inwardly inclined with the end walls and the end portions of the side walls cut to a level below that of the main portions of the side walls and to a level approaching the level of the body of glass in the container to facilitate the radiation of heat from the edges ,of the glass sheet drawn from the receptacle.

4. A container for glass approximating in length the width of the glass sheet to be produced and comprising side and end Walls downwardly and inwardly inclined with the end walls slotted from the upper edge thereof to a level below that of the body of glass in the container and in alinement with the line of generationof the glass sheet to be drawn, the said slot being relatively narrow so that the glass therein solidifies.

5. A container for glass comprising side and end walls downwardly and inwardly inclined, and means for heating the side walls to a higher temperature than the end walls so that the cooling of the edges of the sheet to be drawn as compared with the intermediate portion thereof may be facilitated, and the said container approximating in length the width of the sheet to be produced, so that the edges of the sheet are formed adjacent the end walls of the container.

6. A container for glass approximating in length the width of the glass sheet to be produced and comprising side and end walls downwardly and inwardly inclined, and means for heating the side walls only leaving the end walls to radiate the heat freely and facilitate the cooling of the edges of the sheet drawn.

7 A container for glass approximating in length the width of the glass sheet to be produced and comprising side and end walls downwardly and inwardly inclined, and heating chambers along the side walls only.

8. A container for glass approximating in length the width of the glass sheet to be produced and comprising side walls and end walls of refractory material with the end walls cut to a level below that of the side walls to facilitate the cooling of the edge of the sheet adjacent the line of generation thereof, and heating chambers along the side walls only.

9. A container for glass approximating in length the width of the glass sheet to be produced and comprising side walls and end walls of refractory material with the end walls slotted to a level below that of the body of glass in the container and in alinement with the line of generation of the glass sheet to be drawn, and heating chambers along the side walls only.

10. A container for glass comprising side walls and end walls of refractory material with the end walls cut to a level below that of the side walls to facilitate the cooling of the edges of the sheet adjacent the line of generation thereof, the said side walls being double providing a chamber therein, while the end Walls are of single thickness, and the said container approximating in length the width of the sheet to be produced, so that the edges of the sheet are formed adjacent the end walls of the container.

11. A container for glass comprising side walls and end walls of refractory material with the end walls slotted to a level below that of the body of glass in the container and in alinement with the line of generation of the glass sheet to be drawn, the said side walls being double providing a chamber therein, while the end walls are of single thickness, and the said container approximating -in length the width of the sheet to be produced, so that the edges of the sheet are formed adjacent the end walls of the container.

12. A container for glass comprising side and end walls downwardly and inwardly inclined with the side walls double providing a chamber therebetween while the end walls are of single thickness to permit a more ready radiation of heat, and the said container approximating in length the width of the sheet to be produced, so that the edges of the sheet are formed adjacent the end walls of the container.

13. A container for glass approximating in length the width of the glass sheet to be produced and comprising side and end walls downwardly and inwardly inclined with the side walls double providing a chamber therebctween while the end walls are of single thickness and of such shape as to permit a more ready radiation of heat and lower than the side walls to facilitate the cooling of the edges of the sheet drawn.

In testimony whereof, I have hereunto subscribed my name.

HALBER-T K. HITOHCOCK.

Witness C. S. LAMB. 

